Best defense against it is setting draft order by keepers' salary (either top players or all keepers), so W-L record doesn't affect the draft. Next best is a lottery big enough to take away the incentive to tank. Also helpful is a league with good owners who would notice tanking and call someone on it. Wins floors force teams to draft a reasonable amount if IP/AB, but an owner who wants a top draft pick can reach the wins floor and then tank.

Most the leagues I'm involved with use a formula based on a teams salary, league, and W-L record and reward those who outperform their expectations by the largest margin. If you're interested, there's an entire forum dedicated to improving it that has all of the breakdowns on how it works and where it falls short and I can get you access to it.

For any progressive league I am considering, I ask one simple question: based on how this league allocates draft picks, is it ever advantageous for an owner to lose? If the answer is yes, then I won't join that league. Period. This eliminates for me any league with reverse order of finish draft orders, including ones which use win floors and weighted lotteries. (DIsclaimer - I am in 1 league that does things this way...have been in it since its inception and have a lot of respect for the commissioner...but it is the first league I will drop if circumstances ever require me to play in fewer progs.)